WordNet (r) 3.0 (2006):

uncharted
    adj 1: (of unknown regions) not yet surveyed or investigated;
           "uncharted seas" [syn: chartless, uncharted,
           unmapped]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "uncharted":
   able, enigmatic, incalculable, incognizable, mysterious, puzzling,
   sealed, strange, trackless, unapparent, unapprehended,
   unascertained, unbeknown, unclassified, undisclosed,
   undiscoverable, undiscovered, undivulged, unexplained, unexplored,
   unexposed, unfamiliar, unfathomed, unheard, unheard-of,
   unidentified, uninvestigated, unknowable, unknown, unperceived,
   unplumbed, unrevealed, unsuspected, untouched, virgin